<!doctype html>

<style>
  @keyframes blur-animation {
    from  {
      filter: drop-shadow(10px 10px black);
    } to {
      filter: drop-shadow(10px 10px black);
    }
  }

  #root, #child {
    display: block;
    animation: blur-animation 1s infinite;
  }
</style>

<svg id="root" height="100">
  <rect fill="blue" x="0" y="0" height="100" width="100" />
</svg>
<br>
<svg>
  <rect id="child" fill="blue" x="0" y="0" height="100" width="100" />
</svg>
